{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-47066", "assignerOrgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "state": "PUBLISHED", "assignerShortName": "EEF", "dateReserved": "2026-05-18T17:28:08.321Z", "datePublished": "2026-05-25T14:00:39.707Z", "dateUpdated": "2026-05-25T14:00:39.707Z"}, "containers": {"cna": {"affected": [{"collectionURL": "https://repo.hex.pm", "cpes": ["cpe:2.3:a:benoitc:hackney:*:*:*:*:*:*:*:*"], "defaultStatus": "unaffected", "modules": ["hackney_altsvc"], "packageName": "hackney", "packageURL": "pkg:hex/hackney", "product": "hackney", "programFiles": ["src/hackney_altsvc.erl"], "programRoutines": [{"name": "hackney_altsvc:parse_entries/2"}, {"name": "hackney_altsvc:parse_entry/1"}, {"name": "hackney_altsvc:parse_protocol/1"}, {"name": "hackney_altsvc:parse_token/2"}, {"name": "hackney_altsvc:skip_comma/1"}], "repo": "https://github.com/benoitc/hackney", "vendor": "benoitc", "versions": [{"lessThan": "4.0.1", "status": "affected", "version": "2.0.0-beta.1", "versionType": "semver"}]}, {"collectionURL": "https://github.com", "cpes": ["cpe:2.3:a:benoitc:hackney:*:*:*:*:*:*:*:*"], "defaultStatus": "unaffected", "modules": ["hackney_altsvc"], "packageName": "benoitc/hackney", "packageURL": "pkg:github/benoitc/hackney", "product": "hackney", "programFiles": ["src/hackney_altsvc.erl"], "programRoutines": [{"name": "hackney_altsvc:parse_entries/2"}, {"name": "hackney_altsvc:parse_entry/1"}, {"name": "hackney_altsvc:parse_protocol/1"}, {"name": "hackney_altsvc:parse_token/2"}, {"name": "hackney_altsvc:skip_comma/1"}], "repo": "https://github.com/benoitc/hackney", "vendor": "benoitc", "versions": [{"lessThan": "e548aba1f97ffa3f4750da7b772998fb78c01894", "status": "affected", "version": "408e5fe20302226ea8c74dde2bcbd452d712b5b2", "versionType": "git"}]}], "cpeApplicability": [{"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:a:benoitc:hackney:*:*:*:*:*:*:*:*", "versionEndExcluding": "4.0.1", "versionStartIncluding": "2.0.0-beta.1", "vulnerable": true}], "negate": false, "operator": "AND"}], "operator": "AND"}], "credits": [{"lang": "en", "type": "finder", "value": "Peter Ullrich"}, {"lang": "en", "type": "remediation developer", "value": "Benoit Chesneau"}, {"lang": "en", "type": "analyst", "value": "Jonatan M\u00e4nnchen"}], "descriptions": [{"lang": "en", "supportingMedia": [{"base64": false, "type": "text/html", "value": "Loop with Unreachable Exit Condition ('Infinite Loop') vulnerability in benoitc hackney allows Excessive Allocation.<p>The Alt-Svc response header parser in <tt>src/hackney_altsvc.erl</tt> does not guarantee forward progress. When <tt>parse_token/2</tt> receives a non-token, non-whitespace, non-comma byte (e.g. <tt>!</tt>, <tt>@</tt>, <tt>=</tt>, <tt>;</tt>), it returns the input unchanged. <tt>skip_comma/1</tt> also returns the buffer unchanged when the first byte is not a comma. <tt>parse_entries/2</tt> then recurses with identical data, creating a tight infinite tail-recursive loop that pins a scheduler at 100% CPU. The calling process never returns.</p><p>The entry point <tt>parse_and_cache/3</tt> is called synchronously in the connection process on every HTTP response. A single-byte <tt>Alt-Svc: !</tt> response header is sufficient to trigger the hang; the header is fully controlled by any HTTP origin the client connects to.</p><p>This issue affects hackney: from 2.0.0-beta.1 before 4.0.1.</p>"}], "value": "Loop with Unreachable Exit Condition ('Infinite Loop') vulnerability in benoitc hackney allows Excessive Allocation. The Alt-Svc response header parser in src/hackney_altsvc.erl does not guarantee forward progress. When parse_token/2 receives a non-token, non-whitespace, non-comma byte (e.g. !, @, =, ;), it returns the input unchanged. skip_comma/1 also returns the buffer unchanged when the first byte is not a comma. parse_entries/2 then recurses with identical data, creating a tight infinite tail-recursive loop that pins a scheduler at 100% CPU. The calling process never returns.\n\nThe entry point parse_and_cache/3 is called synchronously in the connection process on every HTTP response. A single-byte Alt-Svc: ! response header is sufficient to trigger the hang; the header is fully controlled by any HTTP origin the client connects to.\n\nThis issue affects hackney: from 2.0.0-beta.1 before 4.0.1."}], "impacts": [{"capecId": "CAPEC-130", "descriptions": [{"lang": "en", "value": "CAPEC-130 Excessive Allocation"}]}], "metrics": [{"cvssV4_0": {"attackComplexity": "LOW", "attackRequirements": "NONE", "attackVector": "NETWORK", "baseScore": 8.7, "baseSeverity": "HIGH", "privilegesRequired": "NONE", "subAvailabilityImpact": "NONE", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "userInteraction": "NONE", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N", "version": "4.0", "vulnAvailabilityImpact": "HIGH", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "NONE"}, "format": "CVSS", "scenarios": [{"lang": "en", "value": "GENERAL"}]}], "problemTypes": [{"descriptions": [{"cweId": "CWE-835", "description": "CWE-835 Loop with Unreachable Exit Condition ('Infinite Loop')", "lang": "en", "type": "CWE"}]}], "providerMetadata": {"orgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "shortName": "EEF", "dateUpdated": "2026-05-25T14:00:39.707Z"}, "references": [{"tags": ["vendor-advisory", "related"], "url": "https://github.com/benoitc/hackney/security/advisories/GHSA-6cp8-v795-jr2j"}, {"tags": ["related"], "url": "https://cna.erlef.org/cves/CVE-2026-47066.html"}, {"tags": ["related"], "url": "https://osv.dev/vulnerability/EEF-CVE-2026-47066"}, {"tags": ["patch"], "url": "https://github.com/benoitc/hackney/commit/e548aba1f97ffa3f4750da7b772998fb78c01894"}], "source": {"discovery": "EXTERNAL"}, "title": "Infinite loop in Alt-Svc header parser in hackney", "x_generator": {"engine": "cvelib 1.8.0"}}}}

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